Balance-staff for watches



No. 451,808. Patented May 5,1891.

W/T/VESSES:

UNITED STATES PATENT OFFICE.

JONATHAN H. COOPER, OF MARSHALL, TEXAS.

BALANCE-STAFF FOR WATCH ES.

SPECIFICATION forming part of Letters Patent No. 451,808, dated May 5, 1891.

Application filed November 10, 1890. Serial No. 370,918. (No model.)

T0 00% whom it may concern.-

Be it knownthat I, JONATHAN H. COOPER, of Marshall, in the county of Harrison and State of Texas, have invented certain new and useful Improvements in Balance-Staffs for Watches; and I do hereby declare that the following is a full, clear, and exact description of the invention, which will enable others skilled in the art to which it appertains to make and use the same, reference being had to the accompanying drawing, and to the letters of reference marked thereon, which form part of this specification.

This invention relates to certain improvements in balance-staffs for watches.

The object of the invention is to strengthen and increase the durability of the pivots or journals of the staff While reducing the frietion to a minimum.

These objects are accomplished by and this invention consists in certain novel features of construction and in combination, of parts more fully described hereinafter, and particularly pointed out in the claims.

The accompanying drawing shows a balance-staff in elevation stripped of all accompanying parts, the bearings for the staff being shown in section. The ordinary staffpivots are cylindrical and very fine and delicate, and easily broken and disarranged by a sudden shock, jar, or fall.

The object of this invention is accomplished by enlarging the bearing in the hole-jewel and employing a balance-staff of enlarged diameter at the journals of a size' to fit the bearings of the hole-jewels, the staff being turned annularly smaller on both sides of a certain point inside of and at about the center of the hole-jewel, thereby leaving a narrow annular bearing-edge engaging the holejewel, hence reducing the surface exposed to Wear, and consequently the friction, down to a minimum. The time-keeping qualities of the watch are thus not affected, and yet the staffjournals are left large enough to give them all necessary strength and render them more durable and better adapted to hard usage.

are formed cone-shaped to prevent engage- The extremities of the staff ment with the hole-jewel and reduce the engaging-surface on the cap-jewel.

In the drawings a indicates the balancestaff having the two similar journal ends mounted in hole-jewels b b and bearing against cap-j ewels c c. Any ordinary or suitable support, such as (Z, carries the jewels, as usual.

cl indicates the large circular bearing-hole through each hole-jewel closed at the outer end by the cap-jewels.

6 indicates the narrow annular bearingedge of each journal located in the hole-jewel at or about the longitudinal center thereof. The staff tapers in opposite directions from said narrow edge, and is hollowed out or annularly recessed, as shown at f, at the inner side of said edge, while the extremity of the staff at the outer side of each edge e is tapered outwardly or formed conical (see 9) and slightly flattened on the end to bear against the cap jewel at 71 with a minimum amount of friction and to prevent longitudinal movement of the staff. By this construction the only points of friction are at h h on the cap-jewels, which prevent longitudinal movement of the staff, and at the narrow sharp annular edges e e on the hole-jewels, which prevent lateral play. It is evident that these narrow edges 6 cause a minimum amount of friction, while the journals of the staff remain of such size as to insure strength and great durability.

The friction of the pivots in the hole-jewels can be regulated by increasing or diminishing the size of the holes in the jewels and the diameter of the pivots, or by increasing or diminishing the diameter of the pivots at the bearing-edge 6.

This invention can be applied to any shaft, the hole-jewel constituting the bearing and the staff the shaft.

The present illustration is enlarged and does not bear the proper proportions of a correctly proportioned and formed balance-staff and jewels.

I-laving fully described my invention, what I claim as new, and desire to secure by Letters Patent of the United States, is-

1. The combination of a hole-jewel with a balance-staff having its portion in the hole of treniity at its point bearing against the cap- 10 said jewel annular-1y reduced on both sides jewel.

of a certain point forming the narrow annu- 1 In testimony that I claim the foregoing as 1m bearing'edge constituting the only bearmy own I affix my signature in presence of ing of the staff on the hole-jewel. two Witnesses.

2. The combination of the hole andcapjew- J. ll. COOPER. els and the balance-staff having the annular Witnesses: narrow edge forming the bearing-edge in the "W. J. ROSBOROUGH, J12, hole of the hole-jewel, and the conical ex- .T. F. DAVIS. 

